The present invention relates to cooling and breathing systems for a subject, and more particularly to on-board cooling and breathing systems for crewman aboard an aircraft which employ a liquid loop cooling garment in conjunction with a breathing gas heat exchanger system.
An oxygen supply system is typically installed in aircraft to provide oxygen to crewmen on board while in flight. One such liquid oxygen system includes a liquid oxygen supply tank or converter containing a quantity of liquid oxygen under pressure. Complete vaporization of the oxygen is accomplished in a heat exchanger which consists of a series of coils of metal tubing exposed to the ambient air surrounding the aircraft and to which oxygen from the supply tank is provided. Oxygen gas leaving the heat exchanger should be of a temperature suitable for breathing when provided to the crewman. While in the heat exchanger, the temperature of the oxygen gas is also raised so that the gas is at a breathable temperature when provided to the crewman. Each crewmember is provided with an oxygen shutoff valve, a seat kit, a regulator, and a face mask with a head strap, for providing him with oxygen. Oxygen gas from the heat exchanger is conducted by supply lines through a console-mounted shutoff valve available to the crewman and thence through each crewman's seat kit which permits quick disconnect of the oxygen line in the event of ejection, and then through an individual regulator, which controls pressure and flow of oxygen gas to the face mask of the crewman.
One prior art method of cooling an aircrewman utilizes an electrical power source to power a motor and air blower unit, and large diameter hoses for routing air from the blower unit to and from the suit worn by the aircrewman. A ventilation ducting system would be incorporated into the crewman's suit. The disadvantages of this system are that a relatively large electrical power drain is required to operate the system, the air temperature is not regulated, and the system is bulky and tends to encumber the airman in the operation of the aircraft.
Another method of cooling an aircrewman uses engine bleed air extracted from a high pressure compressor stage of a turbine of the aircraft engine. Some engine bleed air is passed through an air refrigeration system, and mixed with engine hot bleed air and provided to the suit of the aircrewman. Large diameter hoses are also used in this system for routing the air to and from the airman. Although the air temperature can be regulated, this system cannot be operated unless the aircraft jet engine is in operation or an outside source of compressed air is provided. This system is also bulky and tends to encumber the airman in the operation of the aircraft. Furthermore, in an aircraft where several crewmen are employed, only one crewman, rather than each individual, would control the temperature of the air distributed to the suits of each of the crewmen.